/*
 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package gc.g1.plab.lib;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import jdk.test.lib.Pair;

/**
 * LogParser class parses VM output to get PLAB and ConsumptionStats values.
 *
 * Typical GC log with PLAB statistics looks like:
 *
 * #1: [GC pause (WhiteBox Initiated Young GC) (young) (allocated = 0 wasted = 0 unused = 0 used = 0 undo_waste = 0 region_end_waste = 0 regions filled = 0 direct_allocated = 0 failure_used = 0 failure_waste = 0) (plab_sz = 0 desired_plab_sz = 258)
 * (allocated = 70692 wasted = 1450 unused = 1287 used = 67955 undo_waste = 0 region_end_waste = 0 regions filled = 1 direct_allocated = 19003 failure_used = 0 failure_waste = 0) (plab_sz = 13591 desired_plab_sz = 10193)
 * where first line is statistic for young PLAB and second line is for old PLAB.
 */
final public class LogParser {

    // Name for GC ID field in report.
    public final static String GC_ID = "gc_id";

    /**
     * Type of parsed log element.
     */
    public static enum ReportType {

        SURVIVOR_STATS,
        OLD_STATS
    }

    private final String log;
    private final List<Pair<ReportType, ? extends Map<String, Long>>> reportHolder;

    // GC ID
    private static final Pattern GC_ID_PATTERN = Pattern.compile("#(\\d+):");
    // Pattern for extraction pair <name>=<numeric value>
    private static final Pattern PAIRS_PATTERN = Pattern.compile("\\w+\\s*=\\s*\\d+");

    /**
     * Construct LogParser Object
     *
     * @param log - VM Output
     */
    public LogParser(String log) {
        if (log == null) {
            throw new IllegalArgumentException("Parameter log should not be null.");
        }
        this.log = log;
        reportHolder = parseLines();
    }

    /**
     * @return log which is being processed
     */
    public String getLog() {
        return log;
    }

    /**
     * Returns list of log entries.
     *
     * @return list of Pair with ReportType and Map of parameters/values.
     */
    public List<Pair<ReportType, ? extends Map<String, Long>>> getEntries() {
        return reportHolder;
    }

    private List<Pair<ReportType, ? extends Map<String, Long>>> parseLines() throws NumberFormatException {
        Scanner lineScanner = new Scanner(log);
        List<Pair<ReportType, ? extends Map<String, Long>>> allocationStatistics = new ArrayList<>();
        long gc_id = 0;
        while (lineScanner.hasNextLine()) {
            String line = lineScanner.nextLine();
            // If no any prefix - this is the Old PLAB statistics
            ReportType currentStats = ReportType.OLD_STATS;
            // #NUMBER - this is first line of PLAB statistics
            if (line.startsWith("#")) {
                currentStats = ReportType.SURVIVOR_STATS;
                gc_id = getGcId(line);
            }

            Matcher matcher = PAIRS_PATTERN.matcher(line);
            if (matcher.find()) {
                HashMap<String, Long> map = new HashMap<>();
                map.put(GC_ID, gc_id);
                allocationStatistics.add(new Pair<>(currentStats, map));
                // Extract all pairs from log.
                do {
                    String pair = matcher.group();
                    String[] nameValue = pair.replaceAll(" ", "").split("=");
                    map.put(nameValue[0], Long.parseLong(nameValue[1]));
                } while (matcher.find());
            }
        }
        return allocationStatistics;
    }

    private long getGcId(String line) {
        Matcher number = GC_ID_PATTERN.matcher(line);
        if (number.find()) {
            return Long.parseLong(number.group(1));
        }
        throw new RuntimeException("Should not reach");
    }
}